This Forum should post an easy-to-find instruction sheet of key things to know if you buy a Nexus 7 and have never used Android before. For me, I would have saved many hours of frustration if I knew these three things
1. How to get rid of the white dot that stops you from doing anything when you turn on the Nexus 7. Answer: slide it outside the circle
2. How to turn off the sound. Answer: Push and hold the power button (and then touch "Silent Mode"), or push the bottom button on the right side until the volume gets to minimum and then push once more, or insert earphones into the jack.
3. That I should purchase and read the Nexus 7 Survival Guide
-- with instructions on how to get it on the web or on the Nexus 7 via Google Play Books or Amazon.
While I have owned my Nexus 7 for six weeks, I just found out about the Survival Guide
and had no idea how to do most of the things explained in there.